The reduction of the organic wastes is one of the most critical problems which arises in technologically advanced countries and has been faced in several ways, broadly involving either utilization or distruction of the organic wastes. In recent years, particularly in the United States, the interest of some industries and municipalized concerns has been devoted to the possibility of reducing organic wastes through transformation by the action of the earth-worms.
The action of the earth worms reduces the volume of the organic wastes to a remarkable extent, and may be considered as a substantial means for reducing pollution. The earth worms transform the organic wastes into an excellent odorless fertilizer. Moreover, the production of the earth worms may be considered as a source of protein having nutritional value for animal feed.
The reduction of the organic wastes by means of earth worms is due to the fact that the earth worm and the microflora of its digestive apparatus degrade any organic material through decomposition and remarkably reduce its volume.
Under the same ambient conditions, the degradation rate is a function of the physico-mechanical characteristics of the ambient, which should assure good aeration, of the ratio C/N, optimal from 15 to 35, and, obviously, of the quantity of the earth worms. As a result, a material is obtained which, after drying in the air, is odorless and has a granular consistency.
This material, formed by the dejecta of the earth worms, has the characteristics of a good organic fertilizer. Under optimal conditions, an earth worm degrades par day a quantity of organic substance corresponding to its own weight. It has been demonstrated that the best conditions for increasing the degradation rate are attained when the ratio between the mass of the earth worms and that of the organic material is 1:10. This presents the possibility of utilizing the earth worms for reducing solid urban wastes and cleaner muds.
The applicants have carried out several tests with mixtures of about 50% aerobic or anaerobic muds, and about 50% of solid urban wastes; the mean values of the composition thereof are indicated in the following Table 1.
TABLE 1 ______________________________________ Composition of the aerobic muds, anaerobic muds and solid urban wastes (mean values) S.S. (%) C O.M. Ntot Ptot K20 ______________________________________ Aerobic mud 1.90 31.05 57.09 4.20 3.00 0.90 Anaerobic mud 3.80 41.05 52.25 2.50 1.50 0.80 Solid urban wastes 45.50 34.35 58.12 1.77 0.75 1.02 ______________________________________
The earth worms Lumbricus rubellus have been used in a ratio of 40.000 of worms to 1n.sup.3 of organic material. It has been observed that after 100 days all the organic material has been completely digested by the earth worms.
No negative effects on the earth worms have been noted in the tests performed on anaerobic muds. A remarkable reduction of the material volume of about 40-60% has been observed. At the end of the tests the earth worms have been separated and an increase of 300% of their weight has been noted.
The degradation of the organic wastes depends on both the ratio C/N of the material, the optimal ratio ranging from 15 to 35, and oxygen quantity present in the wastes.
The product obtained from the degradation of the organic wastes by means of the earth worms has the characteristics of a good fertilizer.
Analysis of this fertilizer reveals a remarkable quantity of nutritious elements, which are mineralizable and directly assimilable, a relevant microbic content and the presence of biologically active metabolits, particularly gibberelins, cytokinins and auxins.
On the basic of the test results it may be affirmed that the use of the earth worms for the degradation is a very economical manner for degrading any kind of organic material, particularly urban wastes and cleaner muds.
For carrying out the tests under existing conditions, the invention provides a plant consisting of modular elements which has the purpose of achieving optimal reduction of organic wastes by degradation by means of earth worms, said plant being apt to be utilized with optimal economic yield and having a power variable as a function of the contingent necessities.